The chimeric antigen receptor (CAR) T cell therapy has gradually became a new trend in the treatment of refractory and relapsed hematologic malignancies by developing for 30 years. With the exciting development of genetic engineering, CAR-T technology has subjected to 4 generations of innovation. Structure of CAR-T started from a single signal molecule to 2 or more than 2 co-stimulatory molecules, and then coding the CAR gene or promoter. CAR-T can specifically recognize tumor antigens, and does not be restricted by major histocompatibility complex (MHC), thus making a breakthrough in clinical treatment. In this review, the history, structure and mechanism of action of CAR-T, as well as the current status and challenges of CAR-T immunotherapy in acute lymphoblastic leukemia, acute myeloid leukemia, chronic myeloid leukemia and multiple myeloma are summarized.